Dear Dave,
My fifth wheel is about three years old, and I live in it full-time. While periodically checking my roof, I noticed that some of the sealant around the vents is starting to look aged, but not cracked. How often should I apply new sealant (Dicor) before having to remove the old material and replace it completely? And how hard is it to remove? —Peter, 2021 Grand Design Reflection 337RLS
Dear Peter,
Most RV manufacturers recommend cleaning the roof material and sealants at least once a year, and visually inspecting them for cracks or separation that would allow moisture to penetrate. There is not an actual time frame or schedule to apply or replace, as it all depends on the exposure to the elements.
I believe your roof material is a rubber membrane and most likely Alpha Systems with self leveling lap sealant. The sealant will get darker and grungy looking depending on how much it is exposed to dirt, dust, moisture, and other elements. However, if it is not cracking or separating, it is still doing its job of not allowing moisture to penetrate into the roof structure. You should be able to clean it with Dawn Dish Soap (Blue) and water with a medium-bristle brush. Dawn is best, in my opinion, as it will work on not only dirt but also tree sap and bird droppings.
The roof vent shown above looks pretty nasty. However, it is still sealing the opening and obviously has not had much TLC with cleaning. It would be hard to verify if the sealant was cracked or separated. After this photo was shot, we cleaned the sealant well, inspected it, and also pulled the inside shroud off to verify any leaks. We then installed a MaxxAir vent cover.
How hard is the RV roof sealant to remove?
Again, it depends on the type of sealant and exposure to the elements. Since your unit is only a couple of years old, I would believe the sealant is still fairly pliable and should come off easily. I use a heat gun on a low setting and a plastic putty knife to scrape off the old sealant and not tear the rubber membrane. If the sealant has hardened, it is a much tougher and longer job, while still using the heat gun and putty knife.
This is a photo of the old TV antenna base on the 2015 Thor we worked on. You can see how weathered the sealant is on this one, with some of it actually shrinking and bubbling. We used a razor knife to cut the sealant at the edge of the base to get the plate off, then used the heat gun and razor knife to remove most of the old sealant.
Since we installed a new Winegard Air 360+, we did not need to remove all the sealant as the new dome covered the entire area. However, if we were just resealing, we would have removed more and used mineral spirits to get down to the rubber membrane so the new sealant would adhere better.
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Should I use EternaBond on my RV’s roof vents, A/C units and along seam edges?
Dear Dave,
I’ve been watching a few videos about EternaBond tape and most use it on older RVs. Some have mentioned using it on a new RV around all roof vents, A/C units and along the edges. Is this something that you would recommend? —Bob, 2022 Sportsmen 332BH
Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
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